CVE-2020-1118 Microsoft Windows Transport Layer Security Denial of Service Vulnerability

High 8.6 Published 21 May 2020 Updated 19 Aug 2026

Remote unauthenticated attackers can cause Windows systems to reboot by sending crafted TLS requests, requiring OS patches.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2020-1118?

CVE-2020-1118 is a high-severity denial of service vulnerability in Microsoft Windows 10, published on 21 May 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A denial of service vulnerability exists in the Windows implementation of Transport Layer Security (TLS) when it improperly handles certain key exchanges. An attacker who successfully exploited the vulnerability could cause a target system to stop responding. To exploit this vulnerability, a remote unauthenticated attacker could send a specially crafted request to a target system utilizing TLS 1.2 or lower, triggering the system to automatically reboot. The update addresses the vulnerability by changing the way TLS key exchange messages are validated.

Which versions are affected by CVE-2020-1118?

It affects 2 products.

Products include Microsoft Windows 10, Microsoft Windows Server 2019.

How do I fix CVE-2020-1118?

No fix has been published for CVE-2020-1118 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2020-1118 being exploited?

There is no known exploitation of CVE-2020-1118 in the wild and no public exploit code.

All Microsoft Windows 10 vulnerabilities

Sources

Also known as GHSA-jgvh-pmp6-rc4h.